What do you mean exactly? Been adding skill, but it's not gonna be complete till i do Ex Novels.
There are unknowns like where exactly Julius, Emilia, Priscilla etc stand, because so far have seen no comparison with the others, but in terms of what's known there is a scale.
My opinion: Reid>Reinhard>>>>>>>Peak Wilhelm at his best>>>>>>Peak Wilhelm normally=Kurgan>/=Theresia>>Old Wilhelm, Gluttony>Roswaal J, Grimm, Carol>Garfiel, Elsa.
You get this ability at this level, this stuff doesn't work at that level, that's all there is to it really. Like Grimm on co have perfect skill, which is on the limits of humanity, Old Wil is beyond humanity, Gluttony level can't be reach with a lifetime of training, Theresia goes even further where even an eternities training can't reach, Peak Wil at his best, is far beyond Theresia, but is only on the steps of Reid.
Reinhard can't be reached by Peak Wil, it's said that the they are in different worlds, and basically if the gap between Theresia and everyone else can't be reached in a lifetime or eternity, the gap between Reinhard and Peak Wil is also like that despite him reaching Theresia in 2 years as training, which is absurd.
Reid is at the top cause he is what all swordsman strive towards even Cecilius was talking about Heavenly Sword or whatever in arc 7 i think, not to mention he is at the level where he cuts literal concepts, and despite knowing Reinhard, Julius says Reid is the greatest swordsman recorded in history.